Aim: Children with congenital heart disease (CHD) are at risk of developing neurocognitive problems. However, as these problems are usually identified after cardiac surgery, it is unclear whether they resulted from the surgery or whether they pre-existed and hence might be explained by complications and events associated with the heart disease itself. The purpose of this study was to examine whether neurocognitive deficits commonly reported after cardiac surgery are present before surgery. Method: Forty-five children (22 males, 23 females; mean age 11y 6mo, SD 3y 0mo) with cyanotic and acyanotic heart diseases scheduled for elective cardiac surgery were compared with 41 healthy peers (17 males, 24 females; mean age 11y 10mo, SD 2y 10mo) for attention and processing speed, construction, motor speed, motor planning and fluency, and visual memory. Twenty-three children in the patient group were awaiting their first cardiac surgery and 22 were awaiting follow-up surgery. Results: The patients showed manifest neurocognitive difficulties. Their performance was inferior to that of the healthy comparison group for motor planning (p = 0.02) and visual memory (p = 0.01). The same neurocognitive profile was found in the group of patients awaiting their first cardiac operation. Interpretation: School-age children with various forms of CHD are at risk of neurocognitive impairments before cardiac surgery.